Visible-Light-Mediated Click Chemistry for Highly Regioselective Azide–Alkyne Cycloaddition by a Photoredox Electron-Transfer Strategy

Click chemistry focuses on the development of highly selective reactions using simple precursors for the exquisite synthesis of molecules. Undisputedly, the Cu^I-catalyzed azide–alkyne cycloaddition (CuAAC) is one of the most valuable examples of click chemistry, but it suffers from some limitations as it requires additional reducing agents and ligands as well as cytotoxic copper. Here, we demonstrate a novel strategy for the azide–alkyne cycloaddition reaction that involves a photoredox electron-transfer radical mechanism instead of the traditional metal-catalyzed coordination process. This newly developed photocatalyzed azide–alkyne cycloaddition reaction can be performed under mild conditions at room temperature in the presence of air and visible light and shows good functional group tolerance, excellent atom economy, high yields of up to 99 %, and absolute regioselectivity, affording a variety of 1,4-disubstituted 1,2,3-triazole derivatives, including bioactive molecules and pharmaceuticals. The use of a recyclable photocatalyst, solar energy, and water as solvent makes this photocatalytic system sustainable and environmentally friendly. Moreover, the azide–alkyne cycloaddition reaction could be photocatalyzed in the presence of a metal-free catalyst with excellent regioselectivity, which represents an important development for click chemistry and should find versatile applications in organic synthesis, chemical biology, and materials science.     

Preparation of Lanthanide Hydrides of Nanometric Size by the Catalytic Method

ＩｎｔｒｏｄｕｃｔｉｏｎＬａｎｔｈａｎｉｄｅｈｙｄｒｉｄｅｃａｎｂｅｐｒｅｐａｒｅｄｂｙｄｉｒｅｃｔｈｙｄｒｏ ｇｅｎａｔｉｏｎｏｆｔｈｅｍｅｔａｌｐｒｏｖｉｄｅｄｔｈａｔｉｔｉｓｆｉｒｓｔａｃｔｉｖａｔｅｄｂｙｈｅａｔｉｎｇｔｏ 30 0℃ｉｎｈｙｄｒｏｇｅｎ ,ｆｏｌｌｏｗｅｄｂｙｃｏｏｌｉｎｇｕｎｄｅｒｈｙｄｒｏｇｅｎ .1Ｕｓｉｎｇｔｈｉｓｍｅｔｈｏｄｔｏｐｒｅｐａｒｅｌａｎｔｈａｎｕｍｈｙ ｄｒｉｄｅ ,ｔｈｅｐｒｏｄｕｃｔｈａｓａｎａｖｅｒａｇｅｄｉａｍｅｔｅｒａｒｏｕｎｄ 5 0μｍ ,ａｎｄｉｔｓｓ…     

Surface Functionalization of a γ-Graphyne-like Carbon Material via Click Chemistry

Surface functionalization of carbon materials is of interest in many research fields, such as electrocatalysis, interfacial engineering, and supercapacitors. As an emerging carbon material, γ-graphyne has attracted broad attention. Herein, we report that the surface functionalization of a γ-graphyne-like carbon material ( γ-G1 ) is achieved by immobilizing functional groups via the click chemistry. Texture analysis of aberration-corrected microscopy, X-ray photoelectron spectroscopy, and electrochemistry confirm the successful surface modification of γ-G1 through a strong covalent linkage 1,2,3-triazole. The direct linkage of functional groups on γ-G1 via the click chemistry represents a general method for preparing other functional materials by using γ-graphyne-like materials as a skeleton.     

Preparation of Composite Charge-mosaic Hollow Fiber Membrane by Interfacial Polymerization

The preparation of composite charge-mosaic membrane included spinning of hollow fiber as the supporting membrane, preparing a selective layer on the inside surface of the fiber by interracial polymerization. The charge-mosaic membranes show a high salt permeability while retaining sucrose. The charge-mosaic membrane can be effectively used to separate multivalent salts with organic matter of molecular weight great than 300g/mol in industry.     

Fast Detection of Entacapone by a Lanthanide–Organic Framework with Rhombic Channels

Entacapone (ENT) is a powerful catechol-O-methyl transferase inhibitor that is used for the diagnosis and treatment of Parkinson's syndrome, but the amount used must be well controlled to avoid overtreatment and side effect. Fast and selective detection of ENT needs well-matched energy levels and well-designed sensor-ENT interaction which is highly challenging. In this work, a water stable europium-based metal-organic framework ( Eu-TDA ) was synthesized to detect ENT by luminescence with excellent reusability and selectivity in the presence of main coexisting and interference species of plasma with a limit of detection of 5.01 μM. The experimental results showed that the luminescence of Eu-TDA can be effectively quenched by ENT via well-designed photoinduced electron transfer mechanism and internal filtration effect mechanism in the system.     

Redox Conversions of Polyaniline in Composite Polyaniline–Nafion Polymer Films

Redox processes that occur in composite polyaniline–Nafion films formed on platinum or glassy carbon during the potential cycling are studied by radioisotope and electrochemical methods. Following a change in the conditions and range of potential cycling, the films exhibit a slow relaxation (memory effect).     

A Survey of Strain-Promoted Azide–Alkyne Cycloaddition in Polymer Chemistry

Highly efficient reactions that enable the assembly of molecules into complex structures have driven extensive progress in synthetic chemistry. In particular, reactions that occur under mild conditions and in benign solvents, while producing no by-products and rapidly reach completion are attracting significant attention. Amongst these, the strain-promoted azide–alkyne cycloaddition, involving various cyclooctyne derivatives reacting with azide-bearing molecules, has gained extensive popularity in organic synthesis and bioorthogonal chemistry. This reaction has also recently gained momentum in polymer chemistry, where it has been used to decorate, link, crosslink, and even prepare polymer chains. This survey highlights key achievements in the use of this reaction to produce a variety of polymeric constructs for disparate applications.     

Application of 1′,2,3,3′,4,4′-Hexa-O-benzylsucrose in the Preparation of Sucrose Macrocycles via a Click Chemistry Route: Regioselectivity Study

Abstract

1′,2,3,3′,4,4′-Hexa-O-benzyl-sucrose was applied in the preparation of sucrose-based macrocycles via a click chemistry route. This was realized by protection of the 6′?OH with silyl block followed by elongation of the glucose end with the ?CH₂CH₂N₃ unit. Removal of the silyl block and subsequent propargylation of the released C6′?OH afforded the corresponding synthon, cyclization of which under the click condition provided the desired macrocycle with the expected 1,4-pattern of substituents at the triazole ring.     

Grafting of Poly（lauryl acrylate） onto Nano-silica by ‘Click Chemistry’

Poly（n-alkyl acrylate） with long side groups,namely,poly（lauryl acrylate）（PLA） was synthesized by reversible addition-fragmentation chain transfer（RAFT） polymerization,and the trithioester terminal groups were converted to thiol by reducing reaction.Grafting of the obtained polymer onto nano-silica modified with 3-（methacryloxy）propyl-trimethoxysilane（SiO2-MPS） was conducted by thiol-ene ‘click chemistry＇.PLA was characterized by proton nuclear magnetic resonance（1H NMR） and gel permeation chromatography（GPC）.Fourier transform infrared（FTIR） spectrometry and thermogravimetric analysis（TGA） were used to demonstrate the grafting reaction,and the grafted hairy nano-silica（SiO2-g-PLA） was viewed under a transmission electron microscope（TEM）.According to TGA,grafting ratio and grafting density of SiO2-g-PLA are 30.27％ and 0.013 chain/nm2,respectively.The static water contact angle of SiO2-g-PLA is （80.10±2.97）°,which ensures its hydrophobicity.Dispersion experiment was carried out to confirm its dispersibility in mixed solvents,indicating its potential application in coatings or composites.     

Preparation of Zeolite—metal Composite Membrane

A NaA Zeolite membrane was synthesized on the surface of the stainless steel slab. The membrane was characterized by XRD and SEM. The membrane was continuous and highly intergrown. The size of NaA zeolite crystals was about 5-6μm.     

Preparation of Monodispersed Polymer Microspheres by SPG Membrane Emulsification‐Solvent Evaporation Technology

The membrane emulsification coupled with solvent evaporation was adopted to prepare monodispersed polystyrene (PS) microspheres. Firstly, stable oil‐in‐water emulsion has been successfully obtained by pressing PS solution through SPG membrane into continuous phase at appropriate pressures. Then monodispersed PS microspheres with size of 2–20 µm were obtained following the removal of solvent. The size of the PS microspheres was strongly dependent on the mean pore size of SPG membrane and concentration of PS solution. Furthermore, the effect of emulsion stability, operation pressure and emulsifier on the size and size distribution of microspheres were systemically investigated. Finally, the surface character of PS microspheres was examined via SEM.     

An Efficient Preparation of 2, 3-Disubstituted Indole Derivatives Induced by Low-valent Titanium

An efficient synthesis of 2, 3-disubstituted indole derivatives through low-valent titanium induced reductive cyclization of acylamido carbonyl compounds is described.     

Proton Insertion Chemistry of a Zinc–Organic Battery

Proton storage in rechargeable aqueous zinc-ion batteries (ZIBs) is attracting extensive attention owing to the fast kinetics of H⁺ insertion/extraction. However, it has not been achieved in organic materials-based ZIBs with a mild electrolyte. Now, aqueous ZIBs based on diquinoxalino [2,3-a:2′,3′-c] phenazine (HATN) in a mild electrolyte are developed. Electrochemical and structural analysis confirm for the first time that such Zn–HATN batteries experience a H⁺ uptake/removal behavior with highly reversible structural evolution of HATN. The H⁺ uptake/removal endows the Zn–HATN batteries with enhanced electrochemical performance. Proton insertion chemistry will broaden the horizons of aqueous Zn–organic batteries and open up new opportunities to construct high-performance ZIBs.     

Cleavage of Nucleotides by Lanthanide Metal Complexes

ＩｎｔｒｏｄｕｃｔｉｏｎＳｙｎｔｈｅｔｉｃｎｕｃｌｅａｓｅｓｗｈｉｃｈｅｆｉｃｉｅｎｔｌｙａｎｄｓｅｌｅｃｔｉｖｅｌｙｍａｋｅｎｕｃｌｅｉｃａｃｉｄｓｃｌｅａｖｅｄｕｎｄｅｒｍｉｌｄｃｏｎｄｉｔｉｏｎｓｈａｖｅｍａｎｙｉｍｐｏｒｔａｎｔｐｏｔｅｎｔｉ...     

Mixed-Metal Cluster Chemistry. 27. Coupling of Diphenylbuta-1,3-diyne and CO at Tungsten–Triiridium Cluster Cores

Reactions of WIr₃(CO)₁₁(-C₅H₄R) (R=H, Me) and excess diphenylbuta-1,3-diyne in refluxing toluene afford a large number of products in each case, one of which has been identified as [WIr₃{ ₄- ⁷-C(Ph)C(C CPh)C(Ph)CC(H)CC₆H₄ C(O)-2}(CO)₇(-C₅H₄R)] [R=H (10 %) (1), Me (6 %)] by a single-crystal X-ray diffraction study of 1. The structure of 1 reveals a unique ten-electron-donating ligand which has formed from combination of two diphenylbuta-1,3-diyne units and one carbonyl group, addition of the latter having presumably proceeded by orthometallation of one phenyl group, followed by formal insertion of the carbonyl into the Ir-phenyl linkage. Crystal data for 1.CH₂Cl₂: space group P2₁/n, a = 8.6081(1)Å, b = 39.3638(5)Å, c = 12.3935(2)Å, = 100.4889(5)°, V = 4129.33(10)ų, Z = 4, R = 0.030, R _w = 0.026 for 4982 reflections [I > 2.00(I)]     

Chemistry of nitrosyliron complexes supported by a β-diketiminate ligand

Several nitrosyl complexes of Fe and Co have been prepared using the sterically hindered Ar-nacnac ligand (Ar-nacnac = anion of [(2,6-diisopropylphenyl)NC(Me)](2)CH). The dinitrosyliron complexes [Fe(NO)(2)(Ar-nacnac)] (1) and (Bu(4)N)[Fe(NO)(2)(Ar-nacnac)] (2) react with [Fe(III)(TPP)Cl] (TPP = tetraphenylporphine dianion) to generate [Fe(II)(NO)(TPP)] and the corresponding mononitrosyliron complexes. The factors governing NO transfer with dinitrosyliron complexes (DNICs) 1 and 2 are evaluated, together with the chemistry of the related mononitrosyliron complex, [Fe(NO)Br(Ar-nacnac)] (4). The synthesis and properties of the related cobalt dinitrosyl [Co(NO)(2)(Ar-nacnac)] (3) is also discussed for comparison to DNICs 1 and 2. The solid-state structures of several of these compounds as determined by X-ray crystallography are reported.     

Preparation of nanoparticles of oxides by the citrate–nitrate process

This paper reports preparation of nanoparticles of oxides by the citrate–nitrate process and the effect of metal ions on the thermal decomposition characteristics of the corresponding citrate–nitrate gel precursors. In order to understand the effect of metal ions on the thermal decomposition characteristics of the precursors, we have prepared a series of single component oxides such as MO, where M = Zn, MO₂, where M = Sn, Ce, Zr, and M₂O₃ where M = Al, Fe, Bi. In all the cases the citrate to nitrate ratio was fixed at 0.3. In order to ascertain the decomposition characteristics of the gel samples, TG/DTA studies were performed on the dried gel samples. After complete physico-chemical characterization of the precursors and the calcined products, it could be concluded that the nature of decomposition of the precursors depends largely on the nature of the metal ions. Finally, the advantages of the citrate–nitrate process such as its high degree of reproducibility, its potential for large-scale production of nano-crystalline ceramic oxide powders and its lower cost could be established based on a series of experiments and examples.     

Cluster of International Conferences “Topical Problems of Modern Chemistry”

Russian Chemical Bulletin -     

A Bioorthogonal Click Chemistry Toolbox for Targeted Synthesis of Branched and Well-Defined Protein–Protein Conjugates

Bioorthogonal chemistry holds great potential to generate difficult-to-access protein–protein conjugate architectures. Current applications are hampered by challenging protein expression systems, slow conjugation chemistry, use of undesirable catalysts, or often do not result in quantitative product formation. Here we present a highly efficient technology for protein functionalization with commonly used bioorthogonal motifs for Diels–Alder cycloaddition with inverse electron demand (DA_inv). With the aim of precisely generating branched protein chimeras, we systematically assessed the reactivity, stability and side product formation of various bioorthogonal chemistries directly at the protein level. We demonstrate the efficiency and versatility of our conjugation platform using different functional proteins and the therapeutic antibody trastuzumab. This technology enables fast and routine access to tailored and hitherto inaccessible protein chimeras useful for a variety of scientific disciplines. We expect our work to substantially enhance antibody applications such as immunodetection and protein toxin-based targeted cancer therapies.     

Click and Release Chemistry for Activity-Based Purification of β-Lactam Targets

β-Lactams, the cornerstone of antibiotherapy, inhibit multiple and partially redundant targets referred to as transpeptidases or penicillin-binding proteins. These enzymes catalyze the essential cross-linking step of the polymerization of cell wall peptidoglycan. The understanding of the mechanisms of action of β-lactams and of resistance to these drugs requires the development of reliable methods to characterize their targets. Here, we describe an activity-based purification method of β-lactam targets based on click and release chemistry. We synthesized alkyne-carbapenems with suitable properties with respect to the kinetics of acylation of a model target, the Ldt_fm L,D-transpeptidase, the stability of the resulting acylenzyme, and the reactivity of the alkyne for the cycloaddition of an azido probe containing a biotin moiety for affinity purification and a bioorthogonal cleavable linker. The probe provided access to the fluorescent target in a single click and release step.